Electric switch



v Sept. 3, l1935.

Hf ARNOLD Er AL 2,012,943

ELECTRIC SWITCH Filed April 28, 1954 2 Sheets-Sheet 1 "w3 1." P- 23 V ffj//cdo/:r:

Sept. 3, 1935. H.- ARNOLD Er AL ELECTRIC SWITCH Filed April 28, 1934 2 Sheets-Sheet 2 PatentedD sels.. 3, 1935 UNITED sTATEs PATENT OFFICE ELECTRIC SWITCH Application April 28,

In Germany This invention relates to electric switches, and particularly to a combined switch for controlling both the ignition system and the starting motor of an internal combustion engine.

The circuit of an electric glow plug or plugs for heavy oil engines are usually closed through a switch before starting the engine and opened again after starting. l

In one previous arrangement there is provided for this purpose a switch with two contact points through which flrst the glow plug alone and then it together with the starting motor are connected in circuit to the source of current. However, if, upon starting, the battery voltage falls considerably, the glow plug will be supplied with too little current for proper operation.

One object of the invention is to avoid this dimculty by providing circuit connectionswhereby in the first position of the switch, the glow plug is connected in sexies with a resistance, and in the second position the glow plug together with' the starting motor are connected in circuit with only a part of 'the resistance.

Another object is to provide a novelswitch structure for effecting the above noted double function.

The accompanying drawings disclose by way 'of example one form of the invention. In the drawings:

Fig. l shows a top plan view of the switch box:

Fig. 2 is a longitudinal section taken on line II-lI of Fig. 1;

Fig. 3 is a longitudinal section taken on line llI-III of Fig. 1;

Fig. 4 is a section taken on line IV--IV of Fig. 2;

Fig. 5 is a section on line V-V of Fig. 2;

Figs. 6 and 'i show details of two stay bolts; and

Fig. 8 is a circuit diagram.

The switch housing I is provided with a bottom plate 2 of insulating material upon which are mounted two stationary switch contacts 2, l and a contact spring 5. Above the bottom plate 2, an intermediate plate 9 is held by means of stay bolts t, 1 and t. Plate 9 carries a resistance formed in two parts Il and II. The resistance II has a lower value than resistance It and is constructed in the form of a glow wire positioned below a transparent window I2 in the upper end of housing I. The three stay bolts t, 1 and I are fastened to and insulated from the intermediate plate 8 and are connected at their free ends by means of nuts to the ends of resistances Iii and li.

, On the bottom plate 2, the stay bolts C and I are electrically connected at 2 and 4. The con,

. switch Shaft I6.

1934, Serial No. 723,000

May 31, 1933 7 Claims. (CL 12B-179) tact spring I is conductively connected with a terminal 3| on the exterior of the bottom plate 2 from which a lead extends through coil 34 of an electromagnet to the ground as shown. The stay bolt 8 extends to a terminal I3 on the exterior 5 of the bottom plate 2 to which is fastened a wire leading to four glow plugs in series. The terminal of the last glow plug is grounded as shown.

Upon the intermediate plate 9 is fastened a bushing I5 in which is journaled a switch shaft I6. A cross pin I1 is set in the latter and extends into a slot I8 provided in the Wall of the bushing Il. In a longitudinal bore of the switch shaft IG is inserted a shaft I9 of a hand lever 20, which is coupled by means of a detent 2| with the In the bore of the switch shaft I6 and extending through a square opening in the bottom plate 2, is a shaft 22, non-rotatable but longitudinally moveable against the force of a coil spring 23, to which shaft is fastened the insulating bushing 24. Upon the latter is provided a. contact arm 25 which coacts with the contact spring 5. The insulating bushing 2l also carries, under the influence of spring 26, a two stepped contact bridge 25 21 having ends 28 and 29 of different lengths. The contact arm 25 and the contact bridge 21 are connected by a wire with terminal 3i) arranged exteriorly on the bottom plate 2 to which is fastened a wire leading to one terminal of battery 32. The other terminal thereof is grounded as shown.

If the switch handle 2li is turned clockwise, the switch shaft I6, because of slot I8 guidingcross pin I1, moves downwardly. The shaft 22 is 35 thereby pressed downwardly against the force of spring 22. The longer end 28 of the contact bridge 21 thereby touches the switch contact 3 to which the glow plugs I4 are connected through resistances Iii and II. For thisI switch position a rest 33 is provided in the oblique slot I8 which forms a stop for the cross pin I1.

If the switch handle 20 is turned farther, the two shafts I 6 and 22 move farther downward. The contact bridge 21 is tilted due to, the abut- 45 ment of its long end 28, until its short end 29 is pressed against the switch contact 4. The resistance I0 is thereby short circuited. At the same time the contact arm 25 rests on the contact spring l whereby the circuit of the electromagnet 3l is closed. Through the contact bridge 36 of the latter the circuit of the starting motor I8 is closed.

After starting, the switch lever 20 is turned backto suchanextentthatthecrosspin I1 lies 55 against the stop 33, so that the glow plugs Il are ccnneced in series with the resistances Il and I I. As soon as the engine furnishes its own ignition, the switch lever 20 is released and thereupon is l returned automatically by spring 23 to its rest position in which the circuit of the glow plugs M is open. For this reason it is not possible for the operator to inadvertently leave the glow plug circuit closed after starting.

As long as the glow plugs I4 are in circuit the window I2 is lighted by the glow of resistance I I. The operator thus recognizes that the glow plugs are connected to the battery 32.

It will be seen that the switch possesses but a single handle which serves to control the glow plugs as well as the starting motor. By using a single switch for both connections, a simple construction of the switch box is obtained as well as a simple arrangement preventing improper connection of the glow plugs and starting motor.

What is claimed is:

l. In apparatus for controlling the glow plug and starting motor of an internal combustion engine, a source of current, a switch having two positions, circuit connections whereby in one position the switch connects the glow ,plug to the source of current and in the other position connects the glow plug and the motor to the source of current, and a resistance in the circuit connections, said rst position connecting the glow plug in series with the resistance and said second position disconnecting at least a portion of the resistance.

2. In apparatus for controlling the glow plug and starting motor of an internal combustion engine, a source of current, a switch having two positions, circuit connections whereby in one position the switch connects the glow plug to the source of current and in the other position connects the glow plug and the motor to the source of current, and a resistance in the circuit connections, said ilrst position connecting the glow plug in series with the resistance and said second position disconnecting at least a portion of the resistance, said switch having a shaft longitudinally adjustable against spring pressure and-a tiltable two position contact bridge for the glow plug and a contact for the motor.

3. In apparatus for controlling the glow plug and starting motor of an internal combustion engine, a source of current, a switch having two positions, circuit connections whereby inone position the switch connects the glow plug to the source of current and in the other position connects the glow plug and the motor to the source of current, and a resistance in the circuit connections, said ilrst position connecting the glow plug in series with the resistance and said second position disconnecting at least a portion of the resistance, said switch having a two part shaft, one part of which is adapted for angular as well as longitudinal adjustment and the other part of which carries contacts longitudinally adjustable only.

4. In apparatus for controlling the glow plug and starting motor of an internal combustion engine, a source of current, a switch having two positions, circuit connections whereby in one position the switch connects the glow plug to the source of current and in the other position connects the glow plug and the motor to the source ofv current, and a resistance in the circuit connections, said first position connecting the glow plug in series with the resistance and said second psition disconnecting at least a portion of the resistance, said switch having a shaft longitudinally adjustable by means of an inclined groove with a rest disposed to form a stop in the closing movement of the switch, and also having means to automatically return the switch to rest position.

5. In apparatus for controlling the glow plug and starting motor of an internal combustion engine, a switch having two positions, a housing for said switch, a window in said housing, a resistance in said housing, and circuit connections whereby all the resistance is connected in one position oi the switch and a part of the resistance is disconnected in the second position, said part whichis connected in said second position being visible through the window when incandescent.

6. In an electric switch for controlling the glow plug and starting motor of an internal combustion engine, a two part shaft, a handle connected to one of said parts for angular and longitudinal adjustment thereof, and contacts carried by said second part, said second part being longitudinally adjustable only.

7. In an electric switch for controlling the glow plug and starting motor of an internal combustion engine, a shaft, contacts closed by movement of saidv shaft, a member adjacent said shaft having an inclinedgroove, a member attached to said shaft adapted to project into said groove whereby angular movement of said handle is converted into longitudinal movement of said shaft, and a rest intermediate the length of said groove disposed in such manner that it forms a stop inthe closing movement of the switch.

HEINRICH ARNOLD.- ERICH DOBLER. 

